1 /*
   2  * Copyright (c) 2013, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/g1/g1CardCounts.hpp"
  27 #include "gc/g1/g1CollectedHeap.inline.hpp"
  28 #include "gc/g1/g1CollectorPolicy.hpp"
  29 #include "gc/g1/g1GCPhaseTimes.hpp"
  30 #include "gc/shared/cardTableModRefBS.hpp"
  31 #include "services/memTracker.hpp"
  32 #include "utilities/copy.hpp"
  33 
  34 void G1CardCountsMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
  35   if (zero_filled) {
  36     return;
  37   }
  38   MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_idx), num_regions * HeapRegion::GrainWords);
  39   _counts->clear_range(mr);
  40 }
  41 
  42 size_t G1CardCounts::compute_size(size_t mem_region_size_in_words) {
  43   // We keep card counts for every card, so the size of the card counts table must
  44   // be the same as the card table.
  45   return G1SATBCardTableLoggingModRefBS::compute_size(mem_region_size_in_words);
  46 }
  47 
  48 size_t G1CardCounts::heap_map_factor() {
  49   // See G1CardCounts::compute_size() why we reuse the card table value.
  50   return G1SATBCardTableLoggingModRefBS::heap_map_factor();
  51 }
  52 
  53 void G1CardCounts::clear_range(size_t from_card_num, size_t to_card_num) {
  54   if (has_count_table()) {
  55     assert(from_card_num < to_card_num,
  56            "Wrong order? from: " SIZE_FORMAT ", to: " SIZE_FORMAT,
  57            from_card_num, to_card_num);
  58     Copy::fill_to_bytes(&_card_counts[from_card_num], (to_card_num - from_card_num));
  59   }
  60 }
  61 
  62 G1CardCounts::G1CardCounts(G1CollectedHeap *g1h):
  63   _listener(), _g1h(g1h), _card_counts(NULL), _reserved_max_card_num(0) {
  64   _listener.set_cardcounts(this);
  65 }
  66 
  67 void G1CardCounts::initialize(G1RegionToSpaceMapper* mapper) {
  68   assert(_g1h->max_capacity() > 0, "initialization order");
  69   assert(_g1h->capacity() == 0, "initialization order");
  70 
  71   if (G1ConcRSHotCardLimit > 0) {
  72     // The max value we can store in the counts table is
  73     // max_jubyte. Guarantee the value of the hot
  74     // threshold limit is no more than this.
  75     guarantee(G1ConcRSHotCardLimit <= max_jubyte, "sanity");
  76 
  77     _ct_bs = _g1h->g1_barrier_set();
  78     _ct_bot = _ct_bs->byte_for_const(_g1h->reserved_region().start());
  79 
  80     _card_counts = (jubyte*) mapper->reserved().start();
  81     _reserved_max_card_num = mapper->reserved().byte_size();
  82     mapper->set_mapping_changed_listener(&_listener);
  83   }
  84 }
  85 
  86 uint G1CardCounts::add_card_count(jbyte* card_ptr) {
  87   // Returns the number of times the card has been refined.
  88   // If we failed to reserve/commit the counts table, return 0.
  89   // If card_ptr is beyond the committed end of the counts table,
  90   // return 0.
  91   // Otherwise return the actual count.
  92   // Unless G1ConcRSHotCardLimit has been set appropriately,
  93   // returning 0 will result in the card being considered
  94   // cold and will be refined immediately.
  95   uint count = 0;
  96   if (has_count_table()) {
  97     size_t card_num = ptr_2_card_num(card_ptr);
  98     assert(card_num < _reserved_max_card_num,
  99            "Card " SIZE_FORMAT " outside of card counts table (max size " SIZE_FORMAT ")",
 100            card_num, _reserved_max_card_num);
 101     count = (uint) _card_counts[card_num];
 102     if (count < G1ConcRSHotCardLimit) {
 103       _card_counts[card_num] =
 104         (jubyte)(MIN2((uintx)(_card_counts[card_num] + 1), G1ConcRSHotCardLimit));
 105     }
 106   }
 107   return count;
 108 }
 109 
 110 bool G1CardCounts::is_hot(uint count) {
 111   return (count >= G1ConcRSHotCardLimit);
 112 }
 113 
 114 void G1CardCounts::clear_region(HeapRegion* hr) {
 115   MemRegion mr(hr->bottom(), hr->end());
 116   clear_range(mr);
 117 }
 118 
 119 void G1CardCounts::clear_range(MemRegion mr) {
 120   if (has_count_table()) {
 121     const jbyte* from_card_ptr = _ct_bs->byte_for_const(mr.start());
 122     // We use the last address in the range as the range could represent the
 123     // last region in the heap. In which case trying to find the card will be an
 124     // OOB access to the card table.
 125     const jbyte* last_card_ptr = _ct_bs->byte_for_const(mr.last());
 126 
 127 #ifdef ASSERT
 128     HeapWord* start_addr = _ct_bs->addr_for(from_card_ptr);
 129     assert(start_addr == mr.start(), "MemRegion start must be aligned to a card.");
 130     HeapWord* last_addr = _ct_bs->addr_for(last_card_ptr);
 131     assert((last_addr + CardTableModRefBS::card_size_in_words) == mr.end(), "MemRegion end must be aligned to a card.");
 132 #endif // ASSERT
 133 
 134     // Clear the counts for the (exclusive) card range.
 135     size_t from_card_num = ptr_2_card_num(from_card_ptr);
 136     size_t to_card_num = ptr_2_card_num(last_card_ptr) + 1;
 137     clear_range(from_card_num, to_card_num);
 138   }
 139 }
 140 
 141 class G1CardCountsClearClosure : public HeapRegionClosure {
 142  private:
 143   G1CardCounts* _card_counts;
 144  public:
 145   G1CardCountsClearClosure(G1CardCounts* card_counts) :
 146     HeapRegionClosure(), _card_counts(card_counts) { }
 147 
 148 
 149   virtual bool doHeapRegion(HeapRegion* r) {
 150     _card_counts->clear_region(r);
 151     return false;
 152   }
 153 };
 154 
 155 void G1CardCounts::clear_all() {
 156   assert(SafepointSynchronize::is_at_safepoint(), "don't call this otherwise");
 157   G1CardCountsClearClosure cl(this);
 158   _g1h->heap_region_iterate(&cl);
 159 }